Automatic nail gun



2 Sheets-Sheet 1 R. G. LAUCHER AUTOMATIC NAIL GUN INVENTOR, Richard 6.Laucher.

mild

w. Mm

Feb. 9, 3960 Filed May 3, 1956 ATTORNEX Feb. 9, 196 R. e. LAUCHER2,923,937

AUTOMATIC NAIL GUN Filed May 3, 1956 2 Sheets-Sheet 2 INVENTOR, Richard6. Laucher.

ATTORNEY United States Patent 2,923,937 AUTOMATIC NAIL GUN Richard G.Laucher, Canoga Park, Calif. Application May 3, 1956, Serial No. 582,358

17 Claims. (Cl. 144.4)

V The present invention relates to a fiuid responsive single-actioncylinder or motor with associated valve control mechanism and morespecifically to an air responsive automatic nail gun.

, Prior mechanisms of this type for driving nails have been unwieldy andexcessively heavy which has had a tendency to minimize their use as aportable tool. Also in certain instances they have been designed so thatthe hammer 'rod works against the compressive force of a spring whenmoving from its at rest to its hammering position so that thecompressive force of the spring can be utilized for urging the hammerrod to resume its at rest position. It will be appreciated that in adesign of this type the full weight of the hammer rod cannot be utilizedfor driving the nail. Other designs utilize a double-action cylinder formoving the hammer rod from its at rest to its nail driving position. Itwill be appreciated, however, that it is extremely diflicult to get thedesired rapid movement of the piston and that the inlet and outletopenings into the piston as well as the valve mechanisms mustbeextremely large to effect the rapid movement of the hammer rod to theextent desired. The automatic nail gun of the present invention utilizesthe inertia or kinetic energy of a mass moving at high speeds fordriving a nail into a supporting surface. Through the utilization ofthis principle the tool of applicants invention is approximately only 3pounds in weight and.

tends to move only a minimum amount off the work surface during the naildriving operation.

It is, therefore, a primary object of the present invention to generallyimprove the operation and construction of mechanisms of this type.

A further object of the present invention is to provide a nail gunwherein storage and release of compressed air is accomplished by usingthe shearing force required to shear the ribbon of the ribbon mountednail.

Another object of the present invention is to provide a valve mechanismfor directing air into a pressure chamber and for evacuating the airtherefrom.

A still further object of thepresent invention is to provide a valvemechanism for driving a hammer rod in a nail driving direction andforindexing a plurality of ribbon-connected nails into drivingrelationship with respect to the hammer rod.

Yet another object of the present invention is to provide a mechanism ofthis type which is relatively light in weight, which is relativelysimple in design and which can be easily and economically manufactured.

Further objects and advantages will become readily apparent to thoseskilled in the artupon perusal of the following description anddrawings, in which:

Fig. l is a side elevational view of a nail gun embodying the principlesof the present invention, with parts broken away to show details inconstruction.

Fig. 2 is a vertical sectional view taken on the line 2-2 of Fig. 1,with parts broken away.

Fig. 3 is a vertical sectional view taken on the line 3- -3 of Fig. 1,with parts broken away. a

Figs. 4, 5 and 6 are views similar to Fig. 1, with parts broken away,showing actuation of the valve mechanism and movement of the hammerrodfrom its at rest posi tion to its hammering position.

Fig. 7 is a cross-sectional view taken on the line 7-7 of Fig. 1.

Fig. 8 is a horizontal sectional view taken on the line 8-8 of Fig. 1.

Referring to Fig. 1 of the drawings, theprinciples' of the presentinvention are shown as applied to an air driven automatic nail gun 10-which broadly consists of a housing 11 which comprises a cylinderportion 12, a valve housing portion 13, and a suitable handle 14. Thehousing is preferably cast of any suitable light material such as forinstance aluminum and comprises a closed end pressure chamber 15 and anopen end cylinder 16, each of these being coaxially aligned. A piston 17is slidably received in the cylinder 16 and consists of a piston head 18and a hammer rod 19 coaxially threadedly received by the piston head, asuitable seal 20 being received in an annular groove 21 formed on thecircumferential surface of the piston head18 for well known purposes.The upward travel of the piston 17 in the cylinder 16 is limited by astop or shoulder 22 formed adjacent the upper circumferential edge ofthe cylinder 16, and as will be readily understood and more fullyexplained hereinafter, the hammer rod 19 is movable in a nail drivingdirection in response to pressure delivered into the pressure chamber15.

The open end of the cylinder 16 threadedly receives a suitable end plate23 and an axial opening '24 is formed in the end plate for receiving theend of the hammer rod 19 and for permitting the hammer rod to passtherethrough. The end plate 23 also has an air opening 25 formed thereinfor connecting the cylinder 16 with the atmosphere, and an opening 26for slidably receiving one end of an index rod 27, the other end of theindex rod being received in an opening 28 formed in the base of thevalve housing portion 13 so that the index rod 27 is slidable in adirection substantially normal to the axis of the hammer red. I

A plurality of nails 29 are received in a nail strip 30 which ispreferably formed of sheet metal such as for instance low carbon steel.The nail strip 30 is in the form of a ribbon and is formed withalternating index grooves 31 and nail head washers 32, the nail headwashers being suitably apertured so as to support the nails, which arewelded therein, in a downwardly depending direction, see Fig. 8. Thenail strip or ribbon 30 is slidably carried in a nail cartridge 33, seeFigs. 2 and 3, which is substantially U-shaped in cross section and canbe formed as an extrusion of any suitable'material or as a stamping. Thecartridge provides a pair of supporting surfaces 34 for supporting theopposite edges of the nail ribbon for indexed movement, and a suitablecover 35 is provided for enclosing the nails and nail ribbon in thecartridge. The cartridge 33 is suitably releasably attached in anyconventional or preferred manner with the valve portion housing 13 so asto be in nail-feeding relationship to the hammer rod 19 as will be morefully appreciated hereinafter.

Referring particularly to Figs. 2 and 7, a pair of shear plates 36 arefixed by suitable screws 37 to the bottom surface of end plate 23 inspaced apart relationship so as to provide a groove 38 for permittingindexed movement of the nails to the hammer rod, a circular opening 39for passage of the hammer rod 19 therebetween and defining a shear edgefor cooperation with the end of the hammer rod and a pair of oppositelyaligned shear edges 40 connecting with opening 39 for cooperation with ashear edge 41 of a knife 42 suitably fixed to the G116,

3 of the hammer rod 19 and movable in an opening in plate 23.

The opening 39 is sufiicient to allow the nail head washer 32 rd passtherethrough when the hammer rod is urged against thenail head with aforce sufficient to shear the washer 32 from the ribbon 30' as will bemore fully appreciated hereinafter. Upon initial movement of the rod 19,the end of the rod will shear the portion 320 connecting the washer withthe side of the ribbon 30. After initial movement of the rod, the knife42 will cooperate with the straight shear edges 40in order to cut oh theends of the ribbon from which the previous washer has been cut. Thedischarge end of the nailicartridge has fixed thereto a protectivetubular shield 42a for enclosing the nail 29' being driven into asupporting surface 43 andthehammer rod 19 when the gun is in operation.I

The end of the index rod slidably receivedin the piston plate has a'radial opening or groove 43a formed therein and an index pawl 44-is'swingablysupported therein by a suitably pivot pin 45. A spring seat46 is '50 located .that the compressive force of a spring 47 urges thepawl 44 to move into engaging relationship with respect to the indexgrooves 31 formed in the nail ribbon 30 so that axial movement of theindexrod to the left, as viewed in Fig. 1, will move the nail ribbon ina like direction relative to the nail cartridge. The compressive forceof a coiled spring 48 urges the index rod to move to the left and whenthe index rod has traveled to the end of opening 26 the foremost nail ofthe nail ribbon is located immediately below the hammer rod.

7 As previously suggested, a valve mechanism 49 is provided forautomatically indexing the nail ribbon and for driving the hammer rodand the nail in a nail engaging position with respect to the supportingsurface. The valve mechanism in the present instance comprises a gun'trigger 50 which is in the form of a piston and which is slidablyreceived in a cylindrical opening 51 formed in the valve housing portion13. The gun trigger 50 has an axial opening 52 formed therein whichreceives the shank 53 of an ejector piston assembly 54. Theejectorpiston 54 has a piston head 55 which is slidable on the walls of thecylindrical opening 51 and an annular groove 56 formed therein forreceiving a suitable seal 57 for well known purposes. The cylindricalopening 51 adjacent the face of the piston head 55 is in'the form of apressure chamber 57a wherein sulficient air pressure is directed toreact against the head 55 to urge the ejector piston 54 to move in anindexing direction. The ejector piston 54 also has an axial opening 58and a nozzle 59 located therein with an orifice opening 60 therethrough.The circumferential surface of the gun trigger or piston 50 has anannular ring 61 which moves into abutting relationship with respect to ashoulder 62 formed on the inner circumferential surface of thecylindrical opening 51 so as to limit upward movement of the triggerrelative to the opening. The trigger also has an annular groove 63 forreceiving-a suitable O-ring or seal 64 adjacent the upward end thereofand an annular groove 65 for receiving a ring or seal 66 adjacent theannular ring 61.

The handle 14 is suitably connected to an air hose 67 which in turn isconnected with a source of compressed air, and an opening 68 is formedin the handle which opens into the cylindrical opening 51 adjacent anannular groove 69 formed on the circumferential surface of the trigger50. A pair of cross ports 79 lead from the annular groove 69 and openinto the axial opening 52 of the trigger. A pair of cross ports 71 arealso formed in the shank 53 of the ejector piston 54 adjacent the outletopening of the nozzle 59 and a pair of O-rings 72 and 73 are received inannular grooves 74 and 75 formed on opposite sides of these cross ports71. A seal 75a is also located adjacent the upper end of shank53 in anannular groove "75b".

pin 78 to one leg 79 of a bell crank The pressure chamber isinterconnected with the cylindrical opening 51 adjacent the piston stop22 by a port 76 so that compressed air can be directed into the pressurechamber for actuating piston 17 in a manner which will be fullydescribed hereinafter, and the ejector piston assembly 54 has adownwardly extending tubular leg portion 77 which is pivotallyconnectedby a suitable 80. The bell crank 30 is mounted so as to rock about theaxis of a suitable supporting pin 81 carried by the valve-portionhousing 13 and the other leg 82 of the bell crank 80 is pivotally Iconnected by means of a suitable pin 83 to the index rod 27 so that theindex ro'd will be urged to move against the force exerted by the coiledcompression spring 48 in response to downward movement of the ejectorpiston assembly 54. It will be appreciated that the pawl 44 is sodesigned that its engageable end book 84 will be caused to move totheright over the nail head and the nail ribbon upon movement of thepistonrod to the right. Since the nail gun is designed so as to driveonly one nail at a time, it is necessary to provide means in the path oftravel of said hammer rod whereby only one nail will be indexed to moveinto driving relationship with respect to the hammer rod after eachnailing operation has been completed and this is efiected by a screw 85which is positioned in abutting relationship to the leg 82 of the bellcrank 80 so as to limit the rocking of the bell. crank. in thisdirection to a predetermined extent: so as to permit the index rod tomove to the right a distance only sufiicient to move the hook of thepawl into.- the index groove of the follow-up nail.

As previously suggested, the basic principle of ap-- plicants automaticnail gun is based on the inert1a of apiston moving at high speeds andthis inertia be ng transmitted into work to drive a nail into asupportingsurface. In the operation of the gun, compressed air,approximately to p.s.i., is supplied to the valve mechanism 49 by way ofhose 67 and port or opening 68. In the normal non-activated position ofthe gun trigger 50, thevalve mechanism and the piston 17 assumes theposition shown inFig. 1 and the compressed air entering the annulargroove 69 is completely trapped by O-rings or seals 64, 65, 72 and 75awhich form a seal against movement of the air into the valve andconsequently holds the air at line pressure.- When the trigger S0 isactivated downwardly by the operator (see Fig. 4) the compressed airpasses. downwardly into pressure chamber 57a and into pressure chamber15 byway of opening 76 wherein it acts against the face of p ston head18. It will also be appreciated that thepressure of the compressed airalso reacts against'the piston head 55 of the ejector piston 54. Sincethe compressed a r can only enter the piston chambers 15 and 57a, theforce exerted against the face of piston head 55 of the ejector pistonis built up to a point sufficient tourge the ejector piston 54 to movedownwardly a distance sufiicient to rock the bell crank 80 against thelimit screw 85, which in turn aspreviously suggested, moves oi' indexesthe tooth 84 of the pawl 44 from its engagement With the index groove 31between the first and second nail to engagement with the index groovebetween the second and third nail (see Fig. 5). Concurrently with this,the air pressure inthe chamber 15 builds up to exert sufiicient force onthe face of the piston head 18 to urge the hammer rod 19 against thehead of the nail located in nail driving position with respect to thehammer rod to hold the strip 30 during indexing of pawl 44 and until thenail head washer 32 is sheared from the nail strip (see Fig. 6). Thenail 29 and its washer 32 are consequently released with the hammer rod19 and the piston head 18. It will be appreciated that the stored energyin the pressure chamber 15 prior to the shearing action of the washerhead 32 from therest of the ribbon 30 is suificient after the s heapingaction has tal enplape to drive the pistonIU ant 141 c nail 29 as arapidly a celerating mass against the supporting surface to be nailed.During movement of the hammer rod 19 downwardly, the shearing edge 41 ofthe knife 42 contacts the nail ribbon 30 and shears off the end strip.An opening 86 is formed in shield 42a for permitting the end strip to bedischarged out of the shield.

As previously suggested the inertia of the mass of the piston head 18,the hammer rod 19 and the nail 29 builds up during travel from the atrest position to the contact of the nail with the supporting surface tobe nailed because of the sudden release of energy in the pressurechamber 15. Since the kinetic energy of this rapidly moving mass isutilized for driving the nail into the supporting surface the piston canbe made of relatively light material and of light construction and thegun can also be made relatively light in weight. It will also beappreciated that by reason of this, a light gun can be utilized fordriving nails which will move only a minimum amount off the work surfacewhile in operation and which in turn minimizes fatigue of the operator.

After the hammer stroke or nailing operation is completed, the operatorreleases the trigger 50 thereby opening the cross ports 71 to thepressure chambers and 57a (see Figure 6). In addition, the cross ports70 are opened so as to direct compressed air into the orifice opening 60of the nozzle 59. It will be appreciated that the compressed air passingthrough the orifice opening 60 of the nozzle 59 acts as a pump and drawsthe air in the pressure chamber 15 through the cross port 71 and intothe atmosphere through passage 58. A low pressure vacuum therefore isdeveloped in the pressure chamber 15 and the piston head 18 is urgedinto its at rest position against limit stop 22 by atmospheric pres sureacting against the bottom face thereof and entering through opening 25of the end plate 23. The .pressure diiferential therefore between thepressure chamber 15 and the atmosphere returns the piston to its at restposition The pressure chamber 57a is also evacuated by the pumpingaction of the nozzle so that the pressure difierential between thischamber and the atmosphere as well as the force exerted by spring 48urges the ejector piston 54 to once againrresume its raised position asshown in Fig. 1 after the end of hammer rod 19 has been returned to itsinitial position above the strip 30. This in turn causes the bell crank80 to be rocked so as to urge the index rodvto move to the left, thepawl indexing the follow-up nail into nail driving relationship withrespect to the hammer rod. It will be appreciated, therefore, that thehammer has once again resumed its at rest position and that the ejectorpiston has once again resumed its non-activated position wherein theseals 64, 65, 72 and 75a act to trap the air at line pressure. It isunderstood that the lower part of housing portion 13 is connected toatmosphere by suitable openings to discharge the air from opening 58.

An O-ring 87 is located adjacent the inner face of end plate 23 forabsorbing the shock of piston head 18 when the same is urged to move inits hammering direction.

It is apparent that the product of pressure stored in chamber 15 and thearea of piston 17 determine the shearing force of the piston and thatthe volume of chamber 15 for a given chamber pressure represents thepotential energy convertible to kinetic energy. Thus, the volume ofchamber 15 can be varied to provide sufficient .driving force forvarious sizes of nails, assuming that the same strip is used.

The present invention utilizes the strip tohold back the piston 17 untilsufiicient potential energy is present in chamber 15. This energy buildsup relatively slowly through the line and valve restrictions. If thisholding action were not present, the piston would start to move 1 thenail immediately upon admission of fluid pressure tion.

G to chamber 15 and after the nail engaged surface 43, the nail gunwould be bodily moved away from thesurface 43 since the reaction energyof the light gun is less than the energy required to drive the nail.

The composition, thickness and shear length of the strip portion 32adetermine the shear force required to free the washer 32 and nail 29from the strip and it is apparent that a suitable strip can be selectedforany given nail gun or that a suitable piston area, chamber volume andline pressure can be selected for a nail gun to utilize any given stripconstruction.

The fluid motor of the present invention, comprising the valve mechanismand piston assembly, can be utilized for various other one directionalload "systems, such as for air clamps, and the ejector return of thepiston assembly provides for quick return. The ejector return has theadvantage that the fluid motor is operated in both directions througha'single cylinder port bya prime pressure source. By utilizing theejector return, a large opening 25 can be utilized to subject one sideof piston head 18 to atmosphere so that pressure will not build upagainst the piston head on its workstroke. With double action pistons,large valving mechanism would be required to control the exhaust andentrance of fluid pressure through such a large opening; It is furtherunderstood that the normal distance between the end of nail 29 and thework surface is suflicient to permit the light piston assembly toaccelerate and transfer the potential energy in chamber 15 to kineticenergy of the light piston.

Various modifications are'contemplated' by those skilled in the artwithout departing from the spirit and scope of the invention ashereinafter defined by the appended claims.

What is claimed is r 1. An automatic nail gun for driving a ribbonconnected nail into a work'surface comprising a hammer rod movable froman at rest position we hammer position, an indexing mechanism biased tomove in one direction for urging said ribbon to move into the path oftravel of said hammer rod sufficiently to locate said nail in drivingrelationship with respect'to said hammer rodwhen said hammer rod is inits at rest position and in elevated-position'with respect to said worksurface, and means for dinail.

2. A nail gun for a ribbon connected nail comprising a fluid responsivesingle action motor including a piston having a hammer rod movable froman at rest position to a work position and a housing for slidablyreceiving said piston,means for slidably carrying said ribbon across thepath of travel of'said hammer rod for positioning said nail adjacent thestriking head of said hammer rod when said hammer rod is in its at restposition and in an ele vated position relative to a work surface, andmeans'for directing fluid pressure into said housing for urging saidhammer rod to move in a work direction, said ribbon resisting movementof said hammer rod from its at rest position until the pressure hasbuilt up sufficiently to cause said hammer rod to shear said ribbon,whereby the sudden release of the stored energy in said housing causesrapid acceleration of said piston and nail in a work direction fordriving said nail into said work surface, said last mentioned meansincluding further means operable after the nailing operation forcreating a vacuum in said housing for causing said piston to resume itsat rest posi- 3. A nail gun for ribbon connected nails comprising 7 afluid responsivev single action motor including a piston havinga hammerrod movable from'an at rest position to a work position and a housingfor slidably receiving said piston, means for slidably carrying saidribbon across the path of travel of said hammer rod for positioning anail adjacent the striking head of said hammer rod when said hammer rodis in its at rest position and in an elevated position relative to awork surface, a valve for directing fluid pressure into'said housing forurging said hammer rod to'move' in a work direction, said ribbonrcsisting movement of said hammer rod from its at rest position untilthe pressure is built up sufliciently to cause said hammerrod toshearsaid ribbon, whereby'the sudden release of the stored energy in saidhousing causes rapidaceeleration of said piston and nail in a workdirection for driving said nail into said work surface, and index meanscontrolled by said valve for moving the follow-up nail in drivingalignment withsaid hammer rod upon said hammer rod resuming'its at restposition.

' 4. A single-action fluid responsive motor for exerting a work force inone direction, a valve for controlling said work force comprising ahousing having a cylindrical opening formed therein and a pressurechamber co-axail with said opening and interconnected with said motor, atrigger slidably received in said opening and movable from anormal nonactivated position to an actuating position, an ejector piston slidablyreceived in said pressurechamber and having a shank telescopicallyreceived bygsaid'trig'ger, said housing havinga duet for directing fluidpressure into said opening, seal means for sealing 's'aid duct at linepressure upon said trigger being in its normal position, said fluidpressure being directed into said pressure chamber for urging saidpiston to move in one direction and into said motor for causing saidmotor to exert said work force upon said trigger assuming its actuatingposition relative to said ejector piston, said pistohbeing tubularinform and said fluid pressure being directed through said piston 'uponsaid trigger resuming its normal position and said'shank having a crossport which moves into an unsealed position whereby said fluid pressurein said pressure chamber and in said motor is evacuated through saidpiston and said piston is urged to move relative to said trigger intoits normal position and said motor is caused to resume its normalnon-activated position.

A single-action fluid responsive motor for exerting a work force in onedirection, a valve for controlling said work force comprising a housinghaving a cylindrical openingformed therein and a pressure chamberco-axial with said'opening and interconnected with said'motor, a'triggerslidably received in said opening and movable from a normalnon-activated position to an actuating position, an ejector pistonslidably received in said pressure chamber and having a shanktelescopically received by said trigger, said housing having a duct fordirecting fluid pressure into said opening, seal means for sealing saidduct at line pressure upon said trigger being in its normal position,said fluid pressure being directed into said pressure chamber for urgingsaid piston to move in one direction and into said motor for causingsaid motor to exert said workforce upon said trigger assuming itsactuating position relative to said ejector piston, said piston beingtubular in form and having a nozzle located therein and said fluidpressure being directed through said nozzle upon said trigger resumingits normal position and said shank having a cross port adjacent saidnozzle which moves into an unsealed position whereby said fluid pressurein said pressure chamber and in said motor is evacuated through saidpiston and said piston is urged to move relative to' said trigger intoits normal position and. said motor is caused to resume its normalnon-activated position, and

force transmitting means connected with said piston for exerting apredetermined force timed relationship with erspectio saidwork "terse.

6. A singleaction fluid responsive motor for exerting a work force inone direction, a valve for controlling said ork force comprising ahousing, a trigger slidably received in said housingand movable from anormal to an actuated position, said trigger having an axial openingformed therein, an ejector piston slidably received in said housing andhaving a shank slidably received by said trigger, means for directingfluid pressure into said housing adjacent said trigger, means forsealing said fluid at line pressure when said trigger is in its normalposition, said fluid pressure being directed into said motor for causingsaid motor to exert said work force when said trigger is moved axiallyin said housing relative to said shank into its actuated position, saidfluid pressure reacting against said ejector piston to cause said pistonto move axially relative to said trigger, said ejector piston havingformed therein a discharge opening and said trigger upon resuming itsnormal position having aport for directing fluid pressure through saiddischarge opening and said shank having a port for interconnecting saidmotor with said discharge opening for creating a vacuum by ejectionaction in said motor.

7. A single action fluid responsive motor for exerting a Work force inone direction, a valve for controlling said workforce comprising ahousing, atrigger slidably received in said housing and movable from anormal to an actuated position, said trigger having an axial openingformed therein, an ejector piston slidably received'in said housing andhaving a shank slidably received in said trigger, means for directingfluid pressure into said housing adjacent said trigger, means forsealing said fluid at line pressure when said trigger is in its normalposition, said fluid pressure being directed into said motor for causingsaid motor to exert said work force when said trigger is moved axiallyin said housing relative to said shank into its actuated position, saidfluid pressure reacting against said ejector piston to cause said pistonto move axially relative to said trigger, said ejector piston havingformed therein a discharge opening with a nozzle located therein andsaid trigger having a port for directing fluid pressure through saidnozzle upon resuming its normal position and said shank having a portlocated adjacent said nozzle for interconnecting said motor with saiddischarge opening for creating a vacuum by ejection pumping action insaid motor.

8. A valve comprising a housing having a cylindrical opening formedtherein and a pressure chamber co-axial Withsaid opening, a triggerslidably received in said opening and movable from a normalnon-activated position to an actuating position, an ejector pistonslidably received in said pressure chamber and having a shanktelescopically received by said trigger, said housing having a duct fordirecting fluid pressure into said opening, seal means for sealing saidduct at line pressure upon said trigger being in its non-activatedposition, said fluid pressure being directed into said pressure chamberfor urging said piston to move in one direction a predetermined distanceupon said trigger assuming its actuating position relative to saidejector piston, said piston being tubular in form and said fluidpressure being directed through said piston upon said trigger resumingits normal position and said shank having a cross port which moves intoan unsealed position whereby said fluid pressure in said pressurechamber is evacuated through said piston whereby said piston is urged tomove relative to said trigger into its normal position.

9. A valve comprising a housing having a cylindrical opening formedtherein and a pressure chamber co-axial with said opening, a triggerslidably received in said opening and movable from a normalnon-activated position to an actuating position, an ejector pistonslidably received in said pressure chamber and having a shanktelescopically received by said trigger, said housing havts, a d st f re t n 'fl d n' e' s'ur qa op ni g. seal-means" forsealiiigsald d'u'ct'atliiipr'essnr upon said trigger being in its non-activated position, saidfluid pressure being directed into said pressure chamber for urging saidpiston to move in one direction a predetermined distance upon saidtrigger assuming its actuating position relative to said ejector piston,said piston being tubular in form and said trigger having a cross portwhich moves into unsealed position for directing said fluid pressurethrough said piston upon said trigger resuming its normal position andsaid shank having a cross port which moves into an unsealed positionwhereby said fluid pressure in said pressure chamber is evacuatedthrough said piston whereby said piston is urged to move relative tosaid trigger into its normal position.

10. A valve comprising a housing having a cylindrical opening formedtherein and a pressure chamber co-axial with said opening, a triggerslidably received in said opening and movable from a normalnon-activated position to an actuating position, an ejector pistonslidably received in said pressure chamber and having a shanktelescopically received by said trigger, said housing having a duct fordirecting fluid pressure into said opening, seal means for sealing saidduct at line pressure upon said trigger being in its non-activatedposition, said fluid pressure being directed into said pressure chamberfor urging said piston to move in one direction a predetermined distanceupon said trigger assuming its actuating position relative to saidejector piston, said piston being tubular in form and having a nozzlelocated therein, said trigger having a cross port which moves intounsealed position for directing said fluid pressure through said nozzleupon said trigger resuming its normal position and said shank having across port adjacent said nozzle which moves into an unsealed positionwhereby said fluid pressure in said pressure chamber is evacuatedthrough said piston and said piston is urged to move relative to saidtrigger into its normal position.

11. A one direction load piston system comprising a fluid motorcontaining a piston, valve means for admitting fluid pressure to saidfluid motor on one side of said piston to drive the piston in thedirection of the load, said valve means comprising a valve membermovable from a normal non-activated position to an activated position toadmit fluid pressure to said fluid motor and an ejector member movablerelative to said valve member upon admission of said fluid pressure tosaid fluid motor, and passage means in said valve member and saidejector member for connecting said ejector member with said fluidpressure and with said fluid motor upon return of said valve member toits normal non-activated position in order to evacuate said fluid motorand return said piston, and means operable upon return of said piston toreturn said ejector member to its original position with respect to saidvalve member.

12. A one direction load piston system comprising a fluid motor open atone end and containing a piston, a valve means movable to admit fluidpressure to the other end of said fluid motor to drive the piston in thedirection of the load, and ejector means movable relative to said valvemeans and connected with said other end of said fluid motor and withsaid fluid pressure after movement of said piston in the load directionin order to evacuate said fluid motor and return said piston.

13. In a tool for driving a fastening element into a Work surface, thecombination of a hammer movable from an at rest position to a workposition, a shearable ribbon for carrying said fastening element, meansfor supporting said ribbon across the end of said hammer when saidhammer is in its at rest position for locating said fastening element inalignment with said hammer, and means for accumulating drive forceagainst said hammer so as to actuate the same, said ribbon holding saidhammer at its at rest position after actuation against movement untilthe force accumulated thereagainst is suflicient to shear said ribbonand drive said hammer as a rapidly accelerating mass.

14. In a tool for driving a fastening element into a work surface, thecombination of a hammer movable from an at rest position to a workposition, a shearable ribbon for carrying a plurality of said fasteningelements, means for supporting said ribbon across the end of said hammerwhen said hammer is in its at rest position for locating the foremostfastening element in alignment with said hammer, means for accumulatingdriving force against said hammer so as to actuate the same, said ribbonholding said hammer at its at rest position after actuation againstmovement until the force accumulated thereagainst is sufficient to shearsaid ribbon and drive said hammer as a rapidly accelerating mass, andmeans associated with the last mentioned means for progressively feedingsaid ribbon across the path of travel of said hammer upon said hammerresuming its at rest position for again locating the then foremostfastening element in alignment with said hammer.

15. An automatic nail gun for driving a ribbon connected nail into awork surface comprising a hammer movable from an at rest position to awork position, means for directing fluid pressure against said hammerfor urging said hammer to move in its work direction, and supportmeansfor carrying said ribbon for positioning said nail in an elevatedposition relative to said work surface and in driving alignment withsaid hammer, said ribbon extending into the path of travel of saidhammer for holding said hammer in its at rest position against movementuntil the fluid pressure accumulated against said hammer is suflicientto cause said hammer to shear said ribbon and permit conversion of thepotential energy of the fluid pressure to kinetic energy of said hammerand said nail for driving said nail into such work surface.

16. A gun for driving a ribbon connected fastening element into a worksurface comprising a fluid responsive single-action motor including apiston having a hammer movable from an at rest position to a Workposition and a housing for slidably receiving said piston, means forslidably carrying said ribbon so that it extends across the path oftravel of said hammer for positioning said fastening element adjacent tothe striking head of said hammer when said hammer is in its at restposition and in an elevated position relative to a work surface, meansfor directing fluid under pressure into said housing for theaccumulation of potential energy therein for urging said hammer to movein a work direction, said ribbon holding said hammer in its at restposition against movement until the fluid pressure has accumulatedsuflicient- 1y to cause said hammer to shear said ribbon, whereby thesuddent release of the accumulated potential energy in said housingcauses rapid acceleration of said piston and fastening element in a workdirection for driving said fastening element into said work surface.

17. In an impact tool for individually sequentially driving a pluralityof fastening elements carried by a strip having a plurality of shearableresistance portions of predetermined strength, each of such resistanceportions normally retaining a corresponding one of said elements in saidstrip, the combination comprising driving means normally held in an atrest position and movable to drive said fastening elements, means foraccumulating potential energy for applying an increasing static force tosaid driving means while said driving means is in its at rest positionand for moving said driving means, means for supplying fluid pressure tosaid accumulating means for providing the desired potential energythereto, and means for cooperably sequentially aligning said drivingmeans and individual ones of said fastening elements in the path oftravel of said driving means and for holding said fastening elementsspaced in an elevated position relative to a working surface at adistance suflicient substantially to convert said potential energy intokinetic energy in said driving means for driving said fastening elementinto said work surface and whereby with'said driving rrieans hoiding"said driving means in its at rest pbsition until said'static forceuponsaid driving means causes shearing ofjsaid cbrrespbnding resistanceportion upon the accumulation of sufficient potential energy by saidaccurnulating means for driving said individual fastening elsrnent iutose iid wOik su'rface. R'eferences Cited in the'fi le o f this patent VUNIIEDL A ES NT 2. 1,169,386 E1; 1 Jan. 25, .1916

12 Stgvens et-a1. 'Decp2 9, 1925 Shafi "June- 21, 1927 Davis Dec. 11',1934 Rossmann Aug. 21, 1945 Kendall July 20, 1948 Puerner Aug. 4, 1953Stebbings Jan. 11, 1955 FOREIGN PATENTS Great Britain Oct. 14, 1893

